Shell Wax is a wax glue that is used for snails. It only appears in the episode "Karate Island" and is used by SpongeBob to clean Gary's shell.
It comes in a small orange and yellow bottle. It has an illustration of a snail who looks similar to Gary on it. In dark green text, the bottle reads the product's name in capital letters.
Role in episode
SpongeBob douses himself in the wax. He then rubs his back all over Gary's shell. When he finishes, his back is completely burned away.